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D.G. Hunter, D.S. Nassif, B.C. Walters, B.I. Gramatikov, D.L. Guyton; Simultaneous Detection of Ocular Focus and Alignment Using the Pediatric Vision Screener . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4833.
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Purpose: Amblyopia responds best if treated early in life, but non-specialists do not reliably identify children at risk. There is a need for a screening device that detects amblyopia risk factors by assessing interocular alignment and ocular focus simultaneously. Methods: Instrument Design: Retinal birefringence scanning (RBS) detects ocular fixation using analysis of polarized light scanned around the birefringent fibers emanating from the fovea. The focus detection system (FDS) detects focus without measuring refractive error by imaging ocular reflections from a point source of light onto a bull’s eye photodetector. The Pediatric Vision Screener measures binocular RBS and binocular FDS to detect focus and alignment from 40 cm. Participants: 18 subjects aged 24 to 52 years, including 14 controls (5 with minimal refractive error, 7 contact-lens-corrected myopes, and 2 spectacle-corrected myopes) and 4 patients (3 with esotropia and 1 with intermittent exotropia; one a contact-lens-corrected myope and 2 LASIK-corrected myopes.) Study design: Visual acuity, ocular motility, sensory status, and refractive error were assessed by an orthoptist. Using the device, central fixation was assessed both binocularly and monocularly, and the subject was asked to fixate binocularly in four ordinal directions 1.5 degrees away from the center. Results: Bilateral simultaneous foveal fixation was detected in all control subjects while only unilateral fixation was detected in the subjects with strabismus. The subject with intermittent exotropia showed alternating right and left "passing" and "failing" scores. For all subjects, no false "passing" readings were produced during paracentral fixation. Focus detection results were more variable and will be presented separately. Conclusions: The Pediatric Vision Screener was able to differentiate between normal binocular alignment and strabismus in cooperative adult subjects. Evaluation of additional subjects with varying degrees of strabismus will help determine the sensitivity to and specificity for small amounts of misalignment in anticipation of larger scale studies in pediatric populations. Grant identification: Research to Prevent Blindness [Lew R. Wasserman Merit Award (DGH), (DLG)], NIH EY-12883 (DGH), Roy and Niuta Titus Foundation (DGH), Helena Rubinstein Foundation (DGH), Alcon Research Institute (DLG), Thomas Wilson Sanitarium (DLG)
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